Methods and systems for digital mammography imaging

ABSTRACT

Various methods and systems are provided for reducing blur in a diagnostic image. In one example, a method includes reducing blur in a diagnostic image by applying a deconvolution filter to the diagnostic image, the deconvolution filter generated from a point spread function (PSF) estimation of blur at each pixel of the diagnostic image, the PSF estimation generated based on a motion vector field between the diagnostic image and a pre-shot image acquired prior to the diagnostic image.

FIELD

Embodiments of the subject matter disclosed herein relate to medicalimaging, and more particularly to digital mammography imaging.

BACKGROUND

Mammography is a medical imaging procedure that includes x-ray imagesfor detecting the presence of one or more tumors or lesions in a breast.In digital mammography, a scout or pre-shot image may be taken of apatient to determine an x-ray technique (e.g., x-ray tube current andvoltage, exposure time) to acquire images of the patient having asufficient brightness. Upon determination of the x-ray technique, one ormore x-ray images of the patient may be acquired. In some examples,multiple x-ray images may be acquired at different view angles and/or atdifferent energy levels.

BRIEF DESCRIPTION

In one embodiment, a method includes reducing blur in a diagnostic imageby applying a deconvolution filter to the diagnostic image, thedeconvolution filter generated from a point spread function (PSF)estimation of blur at each pixel of the diagnostic image, the PSFestimation generated based on a motion vector field between thediagnostic image and a pre-shot image acquired prior to the diagnosticimage.

It should be understood that the brief description above is provided tointroduce in simplified form a selection of concepts that are furtherdescribed in the detailed description. It is not meant to identify keyor essential features of the claimed subject matter, the scope of whichis defined uniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 is a schematic illustration of a digital mammography systemaccording to an embodiment;

FIG. 2 is an image registration method according to an embodiment;

FIG. 3 is a flow chart of a method for detecting and reducing theeffects of patient motion induced blur within digital mammographygenerated images according to embodiments disclosed herein;

FIG. 4 schematically shows a process for image registration; and

FIG. 5 schematically shows a process for reducing blur.

DETAILED DESCRIPTION

The following description relates to various embodiments for digitalmammography imaging procedures. Digital mammography imaging proceduresmay include acquiring 2-dimensional (2D) or 3D digital images of thebreast. For example, digital breast tomosynthesis (DBT) is an imagingtechnique for generating cross-sectional images of a breast at highin-plane resolution. During imaging using a digital mammography system,the breast is compressed and low dose x-ray projection images of thebreast at one or more x-ray tube angles may be obtained at a detector.The projection images are then reconstructed as either standard 2Dimages, or the multiple images at different angles may be used toconstruct a 3D volume from which 2D slices may be obtained.

However, during x-ray exposure, patient motion may occur which mayinduce blur artifacts (e.g., blurring) within the reconstructed image.Blurring may obscure significant breast pathology and can necessitaterepeat imaging, thus increasing the radiation dose received by patientsand raising patient anxiety. Steps may be taken to reduce patient motionsuch as improving patient positioning, limiting the potential of patientmovement, and arresting respiration for the exposure duration, yetblurring may still persist. Blur may occur as a result of inadequatebreast compression, patient muscle relaxation, compression paddlemovement, and/or patient movement.

Thus, according the embodiments disclosed herein, a method is providedthat estimates motion vectors at each image pixel by registering apre-shot image (hypothetically with no motion; very short acquisition)and a diagnostic, full dose mammography image. The motion vector fieldcan generate Point Spread Functions (PSF) of blur, at each image pixel.The estimated PSF can then be used to deconvolve motion blur and improvespatial resolution. The image registration may be configured to estimatemotion vectors in high-noise images, and thus may be robust even usingpre-shot images, which are typically high noise images. By leveragingthis technique in pre-shot (noisy) vs full dose mammography images, amotion kernel may be estimated, which can be used to deconvolve motionblur in the full dose mammography images.

FIG. 1 is a schematic illustration of a digital mammography system whichmay be used to acquire diagnostic x-ray images of a patient. FIG. 2 isan image registration method that may be applied to images acquired withthe digital mammography system of FIG. 1 , as shown schematically by theprocess of FIG. 4 . FIG. 3 is a flow chart of a method for reducing blurwithin x-ray images using a motion vector field generated according tothe method of FIG. 2 , as shown schematically by the process of FIG. 5 .

Referring to FIG. 1 , a digital mammography system 100 including anx-ray system 10 for performing a mammography procedure is shown,according to an embodiment of the disclosure. In some examples, thex-ray system 10 may be a tomosynthesis system, such as a digital breasttomosynthesis (DBT) system. In some examples, the x-ray system 10 may beconfigured to acquire dual-energy images, which may facilitate increasedvisualization of certain structures (e.g., vasculature) when the patientis injected with a contrast agent. Further, the x-ray system 10 may beused to perform one or more procedures including digital tomosynthesisimaging, and DBT guided breast biopsy.

The x-ray system 10 includes a support structure 42, to which aradiation source 16, a radiation detector 18, and a collimator 20 areattached. The radiation source 16 is housed within a gantry 15 that ismovably coupled to the support structure 42. In particular, the gantry15 may be mounted to the support structure 42 such that the gantry 15including the radiation source 16 can rotate around an axis 58 inrelation to the radiation detector 18. An angular range of rotation ofthe gantry 15 housing the radiation source 16 indicates a rotation up toa desired degree on either directions about the axis 58. For example,the angular range of rotation of the radiation source 16 may be −θ to+θ, where θ may be such that the angular range is a limited angle range,less than 360 degrees. An exemplary x-ray system may have an angularrange of ±11 degrees, which may allow rotation of the gantry (that isrotation of the radiation source) from −11 degrees to +11 degrees aboutan axis of rotation of the gantry. The angular range may vary dependingon the manufacturing specifications. For example, the angular range forDBT systems may be approximately ±11 degrees to ±60 degrees, dependingon the manufacturing specifications. In some examples, the gantry 15 maybe fixed and may not rotate.

The radiation source 16 is directed toward a volume or object to beimaged, and is configured to emit radiation rays at desired times toacquire one or more images. The radiation detector 18 is configured toreceive the radiation rays via a surface 24. The detector 18 may be anyone of a variety of different detectors, such as an x-ray detector,digital radiography detector, or flat panel detector. The collimator 20is disposed adjacent to the radiation source 16 and is configured toadjust an irradiated zone of a subject.

In some embodiments, the system 10 may further include a patient shield36 mounted to the radiation source 16 via face shield rails 38 such thata patient's body part (e.g., head) is not directly under the radiation.The system 10 may further include a compression paddle 40, which may bemovable upward and downward in relation to the support structure along avertical axis 60. Thus, the compression paddle 40 may be adjusted to bepositioned closer to the radiation detector 18 by moving the compressionpaddle 40 downward toward the detector 18, and a distance between thedetector 18 and the compression paddle 40 may be increased by moving thecompression paddle upward along the vertical axis 60 away from thedetector. The movement of the compression paddle 40 may be adjusted by auser via compression paddle actuator (not shown) included in the x-raysystem 10. The compression paddle 40 may hold a body part, such as abreast, in place against the surface 24 of the radiation detector 18.The compression paddle 40 may compress the body part, and hold the bodypart still in place while optionally providing apertures to allow forinsertion of a biopsy needle, such as a core needle, or a vacuumassisted core needle. In this way, compression paddle 40 may be utilizedto compress the body part to minimize the thickness traversed by thex-rays and to help reduce movement of the body part due to the patientmoving. The x-ray system 10 may also include an object support (notshown) on which the body part may be positioned.

The digital mammography system 100 may further include workstation 43comprising a controller 44 including at least one processor and amemory. The controller 44 may be communicatively coupled to one or morecomponents of the x-ray system 10 including one or more of the radiationsource 16, radiation detector 18, the compression paddle 40, and abiopsy device. In an embodiment, the communication between thecontroller and the x-ray system 10 may be via a wireless communicationsystem. In other embodiments, the controller 44 may be in electricalcommunication with the one or more components of the x-ray system via acable 47. Further, in an exemplary embodiment, as shown in FIG. 1 , thecontroller 44 is integrated into workstation 43. In other embodiments,the controller 44 may be integrated into one or more of the variouscomponents of the system 10 disclosed above. Further, the controller 44may include processing circuitry that executes stored program logic andmay be any one of a different computers, processors, controllers, orcombination thereof that are available for and compatible with thevarious types of equipment and devices used in the x-ray system 10.

The workstation 43 may include a radiation shield 48 that protects anoperator of the system 10 from the radiation rays emitted by theradiation source 16. The workstation 43 may further include a display50, a keyboard 52, mouse 54, and/or other appropriate user input devicesthat facilitate control of the system 10 via a user interface 56.

Controller 44 may adjust the operation and function of the x-ray system10. As an example, the controller 44 may provide timing control, as towhen the x-ray source 16 emits x-rays, and may further adjust how thedetector 18 reads and conveys information or signals after the x-rayshit the detector 18, and how the x-ray source 16 and the detector 18move relative to one another and relative to the body part being imaged.The controller 44 may also control how information, including images 42and data acquired during the operation, is processed, displayed, stored,and manipulated. Various processing steps as described herein withrespect to FIGS. 2 and 3 , performed by the controller 44, may beprovided by a set of instructions stored in non-transitory memory ofcontroller 44.

Further, as stated above, the radiation detector 18 receives theradiation rays 22 emitted by the radiation source 16. In particular,during imaging with the x-ray system, a projection image of the imagingbody part may be obtained at the detector 18. In some embodiments, data,such as projection image data, received by the radiation detector 18 maybe electrically and/or wirelessly communicated to the controller 44 fromthe radiation detector 18. The controller 44 may then reconstruct one ormore x-ray images based on the projection image data, by implementing areconstruction algorithm, for example. The reconstructed image may bedisplayed to the user on the user interface 50 via a display screen 56.

The radiation source 16, along with the radiation detector 18, formspart of the x-ray system 10 which provides x-ray imagery for the purposeof one or more of screening for abnormalities, diagnosis, dynamicimaging, and image-guided biopsy. For example, the x-ray system 10 maybe operated in a mammography mode for screening for abnormalities.During mammography, a patient's breast is positioned and compressedbetween the detector 18 and the compression paddle 40. Thus, a volume ofthe x-ray system 10 between the compression paddle 40 and the detector18 is an imaging volume. The radiation source 16 then emits radiationrays on to the compressed breast, and a projection image of the breastis formed on the detector 18. The projection image may then bereconstructed by the controller 44, and displayed on the interface 50.During mammography, the gantry 15 may be adjusted at different angles toobtain images at different orientations, such as a cranio-caudal (CC)image and a medio-lateral oblique (MLO) image. In one example, thegantry 15 may be rotated about the axis 58 while the compression paddle40 and the detector 18 remain stationary. In other examples, the gantry15, the compression paddle 40, and the detector 18 may be rotated as asingle unit about the axis 58.

Further, the x-ray system 10 may be operated in a tomosynthesis mode forperforming digital breast tomosynthesis (DBT). During tomosynthesis, thex-ray system 10 may be operated to direct low-dose radiation towards theimaging volume (between the compression paddle 40 and the detector 18)at various angles over the angular range of the x-ray system 10.Specifically, during tomosynthesis, similar to mammography, the breastis compressed between the compression paddle 40 and the detector 18. Theradiation source 16 is then rotated from −θ to +θ, and a plurality ofprojection images of the compressed breast is obtained at regularangular intervals over the angular range. For example, if the angularrange of the x-ray system is ±11 degrees, 22 projection images may becaptured by the detector during an angular sweep of the gantry atapproximately one every one degree. The plurality of projection imagesare then processed by the controller 44 to generate a plurality of DBTimage slices. The processing may include applying one or morereconstruction algorithms to reconstruct three dimensional image of thebreast. Furthermore, the x-ray system may be configured to perform aDBT-guided biopsy procedure. Accordingly, in some exemplary embodiments,the system 10 may further include a biopsy device comprising a biopsyneedle for extracting a tissue sample for further analysis.

In some examples, digital mammography system 100 may be configured toperform contrast imaging where contrast agents, such as iodine, can beinjected into the patient that travel to the region of interest (ROI)within the breast (e.g., a lesion). The contrast agents are taken up inthe blood vessels surrounding a cancerous lesion in the ROI, therebyproviding a contrasting image for a period of time with respect to thesurrounding tissue, enhancing the ability to locate the lesion.

The use of a contrast agent can be coupled with images of the ROI takenusing dual-energy imaging processes and technology. In dual-energyimaging, low-energy (LE) and high-energy (HE) images are taken of theROI. In particular, contrast enhanced spectral mammography (CESM) (2D)and contrast enhanced digital breast tomosynthesis (CE-DBT) (3D) imagingmodalities are performed with dual-energy technology. For each view(single view in CESM, multiple views for CE-DBT), a pair of images isacquired: a low-energy (LE) image and a high-energy (HE) image. InCE-DBT, non-paired HE and LE images may be acquired for each view and anHE volume, LE volume, and recombined CE volumes may be reconstructed forthe ROI. For example, the HE and LE views may be interleaved during theCE-DBT scan (alternatively HE, LE, HE, LE, HE, LE, etc.) with a switchfrom HE to LE then to HE again etc., for each angulated position of thex-ray tube. The LE and HE images are usually obtained at mean energiesabove and below the K-edge of the contrast agent. At x-ray energies justabove the k-edge of the contrast agent, the absorption of x-rays isincreased resulting in an increase of contrast from the iodine contrastagent in the HE image.

In dual-energy 3D or stereotactic procedures, LE and HE imageacquisitions are performed, with at least two different positions of theX-ray source with respect to the detector. The images are thenrecombined to display material-specific information with regard to theinternal structure of the tissue being imaged. In the case of 3D CESM,for example, after the injection of contrast medium, dual-energy imagesare acquired at two or more positions of the x-ray tube with respect tothe detector. For each of these tube angulations, the low andhigh-energy images are recombined to produce an image of the contrastmedium surface concentration at each pixel to provide aniodine-equivalent or dual-energy (DE) image(s) (for a single view inCESM, and for multiple views for CE-DBT), which in CE-DBT, are used toreconstruct a 3D volume. Image recombination may be performed based onsimulations of the X-ray image chain, via calibrations on a referencephantom, or any other suitable 3D-reconstruction process. Additionally,in the continuous mode of acquisition where the X-ray tube movescontinuously with interleaved HE and LE images being taken, the LEimages are used to reconstruct a LE 3D volume, and the HE images areused to reconstruct a HE 3D volume, with both volumes being recombinedin a suitable manner to provide an iodine 3D volume. One can as wellimplement an algorithm that combines 3D-reconstruction and HE/LErecombination in a single step.

FIG. 2 is an image registration method 200 that may be applied to imagesacquired by a digital mammography system (e.g. digital mammographysystem 100 of FIG. 1 ) to compare or integrate data obtained withindifferent images from an image set. In some examples, image registrationmay be used as a preliminary step in other image processingapplications, such as the method of de-blurring images generated fromthe digital mammography system described herein (see FIG. 3 ). Method200 may be executed using computer readable instructions stored in thenon-transitory memory of a computing device of a digital mammographysystem (e.g., digital mammography system 100 of FIG. 1 ) or a controllercommunicatively coupled to the digital mammography system (e.g.,controller 44 of FIG. 1 ). In some embodiments, method 300 may beexecuted by another computing device without departing from the scope ofthis disclosure (e.g., an edge device, a picture archiving andcommunication system (PACS)).

At 202, a reference image and a comparative image may be selected froman image set acquired by the digital mammography system. In someexamples, more than one comparative image may be selected. The referenceimage herein may be defined as the image to which the comparative image(or images) is aligned via during image registration. The referenceimage may be a pre-shot image (when the image registration method isperformed to reduce blur in an image according to the method of FIG. 3 )and the comparative image may be a diagnostic image taken at a timesubsequent to the pre-shot image. In other examples, such as during dualenergy imaging, the reference image may be a low-energy image and thecomparative image may be a high-energy image. The reference image andthe comparative image may be images of the same anatomical features/scanplane of the same patient.

At 204, image registration may be performed on the selected images.During image registration, the comparative image may be aligned to thereference image via a spatial domain method. The spatial domain methodmay include selecting control points within the reference image and thecomparative image at 206. The control points may be individual pixels orgroups of neighboring pixels. The control points may be selectedrandomly in one example. In another example, the control points may beselected based on a predefined grid or other pattern. In a still furtherexample, the control points may be selected based on whichpixels/anatomical regions of the comparative image are likely to exhibitmotion-based blurring, such as pixels at edges of anatomical structures.The control points may be at the same location in each of the referenceimage and the comparative image.

At 208, a local shift computation may be performed between the controlpoints of the two images. The local shift computation may indicate, foreach control point of the comparative image, the magnitude and directionof shift of that control point relative to the reference image. Forexample, the local shift computation may generate a motion vector thatcomprises the vector difference between the position x,y (for rows andcolumns) of the same clinical/anatomical feature (e.g., a microcalcification or a lesion) in the two images: dx=x1−x2, dy=y1−y2.

At 210, pixel-wise interpolation may be performed based on the localshift computation. The interpolation may include a first interpolationthat is performed to pass from the motion vectors at each control pointto a motion vector field with motion vectors at every image pixel (e.g.,the pixel wise interpolation 409 in FIG. 4 ). The first interpolationmay include B-spline interpolation or another suitable interpolation.Thus, the first interpolation may include a B-spline interpolation togenerate a motion vector field, as indicated 212, where the motionvector field includes a respective motion vector at every pixel based onthe motion vectors at the control points and may be used to reduce imageblur, as explained below. During image registration, a secondinterpolation may be performed where, for every pixel p (xp, yp) in thecomparative image (e.g., the image that is being registered), the vectorfield value at pixel p (dx,dy) is used to retrieve the image pixel valuein position (xp+dx, yp+dy) in the same image (because that is where thepixel is supposed to be, according to the reference image). Since dx anddy are not integer values, interpolation is performed on the surroundingpixels using a linear or cubic function, for example, which may create aregistered image.

FIG. 3 is a flow chart of a method 300 for reducing patientmotion-induced blur within x-ray images (e.g., digital mammographyimages) according to embodiments disclosed herein. Method 300 may beexecuted using computer readable instructions stored in thenon-transitory memory of a computing device of a digital mammographysystem (e.g., digital mammography system 100 of FIG. 1 ) or a controllercommunicatively coupled to the digital mammography system (e.g.,controller 44 of FIG. 1 ). In some embodiments, method 300 may beexecuted by another computing device without departing from the scope ofthis disclosure (e.g., an edge device, a picture archiving andcommunication system (PACS)).

At 302, a reference image and a diagnostic image may be acquired by thedigital mammography system. The reference image may be a pre-shot image.The pre-shot image may be a short exposure, low dose image that may havea relatively high amount of noise, and thus may not be suitable for usein diagnostic imaging purposes, but may be used to ensure proper patientpositioning, calculate the full dosage needed to acquire images of atarget brightness, etc. The diagnostic image may be a full dosediagnostic image taken after the pre-shot image. In this way, thediagnostic image may be acquired at a higher radiation dose than thepre-shot image and/or for a longer exposure duration.

At 304, image registration may be performed on the acquired images togenerate a motion vector field. The image registration may be performedaccording to the method of FIG. 2 explained above (e.g., with thediagnostic image being the comparative image described with respect toFIG. 2 ). The image registration may output a motion vector field thatincludes an estimated motion vector for each pixel of the diagnosticimage relative to the pre-shot image.

At 306, a point spread function (PSF) estimation for blur at each pixelof the diagnostic image may be generated based on the motion vectorfield. The PSF may be estimated based on the motion vector fieldobtained from the image registration between the reference image and thecomparative image. For example, for every image pixel, a chosen functionf(p) may be fit using the surrounding motion vector values (from themotion field). This function is the PSF.

At 308, image deconvolution is performed to generate an image withreduced blur. For example, based on the PSF, a deconvolution filter maybe generated and applied to the diagnostic image, resulting in an imagewith reduced blur. For example, the image may be convolved with a filtercalculated from the inverse of the PSF. At 310, the image (e.g., afterapplication of the deconvolution filter) is output for display on adisplay device (e.g., display 50) and/or stored in memory of a computingdevice (e.g., a memory of controller 44 or on a PACS or other suitableimage stored device). Method 300 then ends.

In some examples, method 300 may be performed on all diagnostic imagesacquired with the digital mammography system. In other examples, method300 may be performed only in response to a user request to deblur animage. For example, after a diagnostic image is acquired, the diagnosticimage may be displayed to a user (e.g., a technologist or otherclinician). The user may determine that an unacceptable amount of bluris present and may enter an input (e.g., via a touchscreen, keyboard,etc.) requesting the deblur process of method 300 be applied to reducethe blur in the diagnostic image. In still other examples, method 300may be performed only in response to a determination (e.g., by thedigital mammography system or other computing device) that a diagnosticimage is blurry, which may be based on a sharpness of edges, anartificial-intelligence based model, or another suitable mechanism.

Further, while method 300 was described above as being performed by adigital mammography system, and thus the diagnostic image describedabove may be an image of breast tissue, method 300 may be performed onother types of x-ray images, such as lung images. In such examples,method 300 may be executed on a different type of x-ray imaging system,such as a chest x-ray imaging system.

FIG. 4 schematically shows an example image registration process 400according to an embodiment of the disclosure. The image registrationprocess 400 shown in FIG. 4 may be carried out according to the methodof FIG. 2 . The image registration process 400 includes the registrationof two images, shown at 402. The two images include a reference image401 and a comparative image 403. The reference image 401 may be acquiredat an earlier point in time than the comparative image 403. As explainedabove, the reference image may be a pre-shot image while the comparativeimage may be a full dose diagnostic image.

At 404, the two images are registered by selecting control points,computing a local shift at each control point, and performing apixel-wise interpolation. Example control points 405 and example localshift vectors 407 are shown on comparative image 403. As appreciated byFIG. 4 , the local shift computation may include determination of avector quantifying direction and magnitude of motion/shift for eachcontrol point of the comparative image relative to the correspondingcontrol point of the reference image. The pixels of the comparativeimage are then interpolated on a pixel-wise basis using an interpolationgrid 409. Each pixel may be interpolated based on the pixel values ofneighboring pixels and the motion vectors as described above. The outputof the image registration process 400 is a registered image 406, whichmay in some examples be the comparative image 403 with adjustments madeto some pixels in order to register (e.g., align) features of thecomparative image 403 with the reference image 401.

FIG. 5 shows an example deblurring process 500 according to anembodiment of the disclosure. The deblurring process 500 may be carriedout according to the method 300 of FIG. 3 in order to reducemotion-based image blurring that may occur due to patient movementduring x-ray exposure. The deblurring process 500 includes entering apre-shot image 502 and a full dose image 504 into an image registrationmethod 506. The pre-shot image 502 may be acquired before the full doseimage 504 and may be acquired at a lower radiation dose and/or for ashorter exposure time. As a result, it is assumed that no motionoccurred during acquisition of the pre-shot image, thus allowing thepre-shot image to be a fixed image to which the full dose image 504 maybe compared. The full dose image 504 may be acquired with a longerexposure time and thus may be prone to motion-based blurring. To reducethe blur in the full dose image 504, the full dose image 504 isregistered to the pre-shot image 502 using the image registration methoddescribed above with respect to FIG. 2 and shown schematically in FIG. 4.

The output from the image registration process 506 may be a motionvector field that may be used to estimate a point spread function (PSF)at each pixel, as shown at 508. Based on the PSF for each pixel, adeconvolution filter is generated, which is applied to the full doseimage at 510. The deconvolution of the full dose image results in adeblurred image 512, which may be output for display and/or stored inmemory as part of a patient exam.

The technical effect of using a pre-shot image as a reference image fordeblurring a full dose, diagnostic image is decreased motion-based imageblur and more accurate imaging of patient anatomical features.

An embodiment relates to a method, including reducing blur in adiagnostic image by applying a deconvolution filter to the diagnosticimage, the deconvolution filter generated from a point spread function(PSF) estimation of blur at each pixel of the diagnostic image, the PSFestimation generated based on a motion vector field between thediagnostic image and a pre-shot image acquired prior to the diagnosticimage. In a first example of the method, the diagnostic image is anx-ray image acquired with an x-ray imaging system at a first, higherx-ray radiation dose, and the pre-shot image is an x-ray image acquiredwith the x-ray imaging system at a second, lower x-ray radiation dose.In a second example of the method, which optionally includes the firstexample, the diagnostic image is acquired with a first, longer x-rayradiation exposure and the pre-shot image is acquired with a second,shorter x-ray radiation exposure. In a third example of the method,which optionally includes one or both of the first and second examples,the first x-ray radiation dose is determined based on a brightness ofthe pre-shot image and the second x-ray radiation dose. In a fourthexample of the method, which optionally includes one or more or each ofthe first through third examples, the method further includes outputtingthe reduced blur diagnostic image for display on a display device. In afifth example of the method, which optionally includes one or more oreach of the first through fourth examples, the method further includesgenerating the motion vector field by selecting a plurality of controlpoints in the pre-shot image, calculating a local shift vector for eachcontrol point relative to a corresponding control point in thediagnostic image, and interpolating each pixel of the diagnostic imagebased on each local shift vector to generate the motion vector field.

An embodiment of a method includes acquiring, with an x-ray imagingsystem, a pre-shot image of a patient and a diagnostic image of thepatient; generating a motion vector field by registering the diagnosticimage to the pre-shot image; applying a deconvolution filter to thediagnostic image to generate a reduced-blur diagnostic image, thedeconvolution filter generated based on the motion field vector; andoutputting the reduced-blur diagnostic image for display on a displaydevice. In a first example of the method, the diagnostic image isacquired with the x-ray imaging system at a first, higher x-rayradiation dose, and the pre-shot image is acquired with the x-rayimaging system at a second, lower x-ray radiation dose. In a secondexample of the method, which optionally includes the first example, thediagnostic image is acquired with a first, longer x-ray radiationexposure and the pre-shot image is acquired with a second, shorter x-rayradiation exposure. In a third example of the method, which optionallyincludes one or both of the first and second examples, the first x-rayradiation dose is determined based on a brightness of the pre-shotimage. In a fourth example of the method, which optionally includes oneor more or each of the first through third examples, the deconvolutionfilter is generated based on the motion vector field by estimating apoint spread function for each pixel of the diagnostic image based onthe motion vector field and generating the deconvolution filter based oneach point spread function. In a fifth example of the method, whichoptionally includes one or more or each of the first through fourthexamples, generating the motion vector field comprises selecting aplurality of control points in the pre-shot image, calculating a localshift vector for each control point relative to a corresponding controlpoint in the diagnostic image, and interpolating each pixel of thediagnostic image based on each local shift vector to generate the motionvector field.

An embodiment of an imaging system includes an x-ray source incommunication with a detector; a display device; and a computing deviceconnected in communication with the display device and the detector, thecomputing device including a processor and non-transitory memory storinginstructions executable by the processor to: acquire, with the x-raysource and detector, a pre-shot image of a patient at a first x-ray doseand for a first exposure duration; acquire, with the x-ray source anddetector, a diagnostic image of the patient at a second, higher x-raydose and for a second, longer exposure duration; correct blur in thediagnostic image based on the pre-shot image to generate a reduced-blurdiagnostic image; and output the reduced-blur diagnostic image fordisplay on the display. In a first example of the system, correctingblur in the diagnostic image based on the pre-shot image comprisesestimating a respective motion vector for one or more pixels of thediagnostic image via a registration process with the pre-shot image; andapplying a deconvolution filter to the diagnostic image to generate areduced-blur diagnostic image, the deconvolution filter generated basedon each respective motion vector. In a second example of the system,which optionally includes the first example, generating thedeconvolution filter comprises generating a point spread function foreach pixel of the diagnostic image based on each respective motionvector and generating the deconvolution filter based on each pointspread function. In a third example of the system, which optionallyincludes one or both of the first and second examples, the second x-raydose is determined based on a brightness of the pre-shot image and thefirst x-ray dose.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Moreover, unlessexplicitly stated to the contrary, embodiments “comprising,”“including,” or “having” an element or a plurality of elements having aparticular property may include additional such elements not having thatproperty. The terms “including” and “in which” are used as theplain-language equivalents of the respective terms “comprising” and“wherein.” Moreover, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements or a particular positional order on their objects.

This written description uses examples to disclose the invention,including the best mode, and also to enable a person of ordinary skillin the relevant art to practice the invention, including making andusing any devices or systems and performing any incorporated methods.The patentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those of ordinary skill in the art.Such other examples are intended to be within the scope of the claims ifthey have structural elements that do not differ from the literallanguage of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

The invention claimed is:
 1. A method, comprising: reducing blur in adiagnostic image by applying a deconvolution filter to the diagnosticimage, the deconvolution filter generated from a point spread function(PSF) estimation of blur at each pixel of the diagnostic image, the PSFestimation generated based on a motion vector field between thediagnostic image and a pre-shot image acquired prior to the diagnosticimage, wherein the diagnostic image is an x-ray image acquired with anx-ray imaging system at a first, higher x-ray radiation dose, and thepre-shot image is an x-ray image acquired with the x-ray imaging systemat a second, lower x-ray radiation dose.
 2. The method of claim 1,wherein the diagnostic image is acquired with a first, longer x-rayradiation exposure and the pre-shot image is acquired with a second,shorter x-ray radiation exposure.
 3. The method of claim 1, wherein thefirst x-ray radiation dose is determined based on a brightness of thepre-shot image and the second x-ray radiation dose.
 4. The method ofclaim 1, further comprising outputting the reduced blur diagnostic imagefor display on a display device.
 5. The method of claim 1, furthercomprising generating the motion vector field by selecting a pluralityof control points in the pre-shot image, calculating a local shiftvector for each control point relative to a corresponding control pointin the diagnostic image, and interpolating each pixel of the diagnosticimage based on each local shift vector to generate the motion vectorfield.
 6. A method, comprising: acquiring, with an x-ray imaging system,a pre-shot image of a patient and a diagnostic image of the patient,wherein the diagnostic image is acquired with a first, longer x-rayradiation exposure and the pre-shot image is acquired with a second,shorter x-ray radiation exposure; generating a motion vector field byregistering the diagnostic image to the pre-shot image; applying adeconvolution filter to the diagnostic image to generate a reduced-blurdiagnostic image, the deconvolution filter generated based on the motionvector field; and outputting the reduced-blur diagnostic image fordisplay on a display device.
 7. The method of claim 6, wherein thediagnostic image is acquired with the x-ray imaging system at a first,higher x-ray radiation dose, and the pre-shot image is acquired with thex-ray imaging system at a second, lower x-ray radiation dose.
 8. Themethod of claim 7, wherein the first x-ray radiation dose is determinedbased on a brightness of the pre-shot image.
 9. The method of claim 6,wherein the deconvolution filter is generated based on the motion vectorfield by estimating a point spread function for each pixel of thediagnostic image based on the motion vector field and generating thedeconvolution filter based on each point spread function.
 10. The methodof claim 6, wherein generating the motion vector field comprisesselecting a plurality of control points in the pre-shot image,calculating a local shift vector for each control point relative to acorresponding control point in the diagnostic image, and interpolatingeach pixel of the diagnostic image based on each local shift vector togenerate the motion vector field.
 11. An imaging system, comprising: anx-ray source in communication with a detector; a display device; and acomputing device connected in communication with the display device andthe detector, the computing device including a processor andnon-transitory memory storing instructions executable by the processorto: acquire, with the x-ray source and detector, a pre-shot image of apatient at a first x-ray dose and for a first exposure duration;acquire, with the x-ray source and detector, a diagnostic image of thepatient at a second, higher x-ray dose and for a second, longer exposureduration; correct blur in the diagnostic image based on motion betweenthe pre-shot image and the diagnostic image to generate a reduced-blurdiagnostic image; and output the reduced-blur diagnostic image fordisplay on the display.
 12. The imaging system of claim 11, whereincorrecting blur in the diagnostic image based on the pre-shot imagecomprises estimating a respective motion vector for one or more pixelsof the diagnostic image via a registration process with the pre-shotimage; and applying a deconvolution filter to the diagnostic image togenerate a reduced-blur diagnostic image, the deconvolution filtergenerated based on each respective motion vector.
 13. The imaging systemof claim 12, wherein generating the deconvolution filter comprisesgenerating a point spread function for each pixel of the diagnosticimage based on each respective motion vector and generating thedeconvolution filter based on each point spread function.
 14. Theimaging system of claim 11, wherein the second x-ray dose is determinedbased on a brightness of the pre-shot image and the first x-ray dose.